In recent years the reduction in size of electronic components has been implemented by using high dielectric materials even in high frequency bands of microwaves, semi-millimeter waves, or millimeter waves. For implementation of downsizing of a device, when the shape of the device is reduced into a similar shape while the dielectric constant thereof is increased, there is such a problem that in principle, an energy loss increase in inverse proportion to the cube root of its volume.
The energy loss of high frequency devices can be classified roughly into a conductor loss due to the skin effect and a dielectric loss due to the dielectric material thereof. Dielectric materials that have been developed into practical use in recent years include those having a low loss characteristic even when they have their high dielectric constant, and therefore, the conductor loss rather than dielectric loss is predominant in the no-loaded Q of their circuits. As shown in FIG. 11, a high frequency current concentrates on the conductor surface due to the skin effect, so that the closer to the conductor surface the position is, the more the surface resistance (also referred to as a skin resistance) increases, and this leads to an increased conductor loss (Joule loss).
In view of these circumstances, an improved symmetrical strip line resonator (hereinafter, referred to as a conventional resonator) which is effectively reduced in conductor loss enough to obtain a high no-loaded Q has been proposed in the Japanese Patent Laid-Open Publication No. HEISEI 4 (1992)-43703. The conventional resonator is a symmetrical strip line resonator in which a resonator circuit is made up of symmetrical strip lines having a strip conductor disposed between a pair of earth conductors which are oppositely positioned a predetermined distance away from each other with a dielectric interposed therebetween, wherein the symmetrical strip line resonator is characterized in that a plurality of sheets of strip conductors is disposed between the pair of earth conductors in parallel to the pair of earth conductors so that the plurality of sheets of strip conductors are multilayered so as to be spaced from each other at a predetermined interval with the dielectric interposed therebetween.
The publication which discloses the above-mentioned conventional resonator also discloses the followings:
(a) it is preferably that the respective strip conductors are formed so as to have a thickness three times as thick as or more than the skin depth in order to effectively suppress the conductor loss; that is, in the strip conductors, the skin portion through which a high frequency current of microwave band flows is increased so that the effective sectional area in the strip conductors is increased; PA1 (b) a pair of strip conductors are made to conduct with each other at ends thereof via a through hole while they are made to conduct with each other also at another end via a through hole; and PA1 (c) an electric field distribution of the resonator is formed so that the electric field is directed from each of the strip conductors toward the earth conductors. PA1 thin film conductors and thin film dielectrics are alternately stacked so that a plurality of TEM mode transmission lines are multilayered, each of the TEM mode transmission lines comprising a pair of the thin film conductors between which each of the thin film dielectrics is sandwiched, PA1 wherein, based on a number (n) of multilayered layers of said thin film conductors and the thin film dielectrics, a film thickness of each of the thin film dielectrics is set so that phase velocities of TEM waves which propagate through at least two of the plurality of TEM mode transmission lines are made substantially equal to each other, and PA1 wherein, based on the number (n) of multilayered layers of said thin film conductors and the thin film dielectrics, a film thickness of each of the thin film conductors is made smaller than a skin depth of a frequency which is used so that electromagnetic fields of at least two of the plurality of TEM mode transmission lines are coupled with each other. In this case, each of the thin film conductors is preferably made of a superconducting material. PA1 wherein, based on a number (n) of multilayered layers of the thin film conductors and the thin film dielectrics, a film thickness of each of the thin film dielectrics is set so that phase velocities of TEM waves of TEM waves which propagate through at least two of the plurality of TEM mode transmission lines are made substantially equal to each other, and PA1 wherein, based on the number (n) of multilayered layers of said thin film conductors and the thin film dielectrics, a film thickness of each of the thin film conductors is made smaller than a skin depth of a frequency which is used so that electromagnetic fields of at least two of the plurality of TEM mode transmission lines are coupled with each other. In this case, the high frequency transmission line is implemented by, for example, a waveguide. PA1 a first transmission line; and PA1 at least one TEM mode second transmission line in which a thin film conductor and a thin film dielectric are alternately stacked so that the velocity of an electromagnetic wave which propagates through the first transmission line (L1) and a phase velocity of a TEM wave which propagates through at least one of the second transmission line (L2-L5) are made substantially equal to each other, and PA1 wherein, based on the number (n) of multilayered layers of said thin film conductors (21-25) and said thin film dielectrics (31-34), a film thickness of the thin film conductors (21-25) is made smaller than a skin depth of a frequency which is used so that an electromagnetic field of the first transmission line (L1) and an electromagnetic field of at least one of the second transmission line (L2-L5) are coupled with each other.
However, since it has the above-mentioned structure (a), there is such a problem that it is difficult to reduce the size and weight thereof, and the resonator has a relatively small reduction rate in conductor loss as well as a relatively small no-loaded Q.
Accordingly, the object of the present invention is to solve the above-mentioned problems, and is to provide a high frequency electrode which can remarkably reduce the conductor loss as compared with that of the conventional counterpart, and yet which can reduce the size and the weight of the embodied product of the present invention, and to provide a high frequency transmission line, a high frequency resonator, a high frequency filter, and a high frequency device.